Mechanical apparatus

ABSTRACT

The apparatus includes a guide surface which supports a flexible elongated element in a lobe arched away from the guide surface. Portions of the element on opposite sides of the lobe frictionally engage the surface to prevent the lobe from collapsing. The lobe is capable of progressing along the element to displace the lobe relative to the guide surface. The flexible elongated element is in the form of a thin flexible band. The guide surface may be either flat or concave. Preferably, the band is secured to the guide surface at positions spaced apart from each other a distance substantially greater than the length of the lobe in the band. The lobe may be caused to progress along the guide surface by lifting the band away from the guide surface at either end of the lobe, or by applying a force to the apex of the band in a direction extending longitudinally of the band.

United States Patent [191 [451 March 6, 1973 Wilkes MECHANICAL APPARATUS [75] Inventor: Donald F. Wilkes, Albuquerque, N.

Mex.

[73] Assignee: Rolamite, Incorporated, San Francisco, Calif.

[22] Filed: April 29, 1970 [21] Appl. No.: 32,886

[52] 11.8. CI ..74/l00, 25l/D1G. 2

[51] Int. Cl ..F16h 21/44 [58] Field of Search ..74/100; 251/75, D10. 2; l37/625.28

[5 6] References Cited UNITED STATES PATENTS 2,784,740 3/1957 Stageberg .,25l/DlG. 2

2,989,076 6/1961 Rohmann ..251/DIG. 2

3,467,139 9/1969 Richards ..137/625.48

2,512,306 6/1950 Clark et a1 ..74/l00 3,571,540 3/1971 Richards ..74/l00 2,802,365 8/1957 Hoepfner ..74/l00 2,118,792 5/1938 Horton ..74/100 Primary Examiner-Milton Kaufman Assistant ExaminerWesley S. Ratliff, Jr. Attorney-Bums, Doane, Swecker & Mathis [57] ABSTRACT The apparatus includes a guide surface which supports a flexible elongated element in a lobe arched away from the guide surface. Portions of the element on opposite sides of the lobe frictionally engage the surface to prevent the lobe from collapsing. The lobe is capable of progressing along the element to displace the lobe relative to the guide surface. The flexible elongated element is in the form of a thin flexible band. The guide surface may be either flat or concave. Preferably, the band is secured to the guide surface at positions spaced apart from each other a distance substantially greater than the length of the lobe in the band. The lobe may be caused to progress along the guide surface by lifting the band away from the guide surface at either end of the lobe, or by applying a force to the apex of the band in a direction extending longitudinally of the band.

21 Claims, 17 Drawing Figures PATENTEDHAR. 6 1

sum 10F 3 lNVENTQR DONALD F WILKES BY 301.112 04M I Mid,

5mm M4 ATTORNEYS PATENTED 6% 3 719,097

SHEET 30F .3

no. I3

FIG. I5

MECHANICAL APPARATUS CROSS REFERENCE TO RELATED APPLICATIONS Two related applications of Donald F. Wilkes entitled respectively Snap Action Apparatus Ser. No. 32,885 and Cyclic Apparatus" Ser. No. 32,808 are being filed concurrently herewith. Both disclose related subject matter, and the disclosures thereof are incorporated herein by reference.

BACKGROUND OF THE INVENTION This invention relates to mechanical apparatus, and more particularly to means for effecting relative motions between elements in apparatus.

Various mechanical means are available for effecting relative motion between elements. Examples of such means are levers, cams, screws and springs. Although these conventional means may be capable of producing the desired relative motion between elements, undesirable effects, such as frictional drag, lost motion and insufficient force amplification may make the conventional means unsuitable in some applications. Even in those applications where these undesirable effects can be tolerated, it is usually advantageous to reduce these undesirable effects to a minimum.

Wherever it is possible to provide the required mechanical connection between elements in apparatus by a minimum of separate parts, substantial savings in manufacturing costs and costs of materials are the result. Conventional means often require accessive material and are awkward or expensive to assemble.

SUMMARY THE INVENTION Accordingly, it is an object of this invention to provide a mechanical apparatus that is capable of effecting relative motion between elements efficiently and at a minimum cost. i

A further object of this invention is to provide apparatus for effecting relative motion between elements with a minimum of frictional drag between the elements.

It is a still further object of this invention to provide apparatus for effecting relative motion with a minimum operating force.

Another object of this invention is to provide apparatus for effecting relative motion between elements in which ware of the components is minimized.

It is a still further object of this invention to provide apparatus for effecting a large amplification of motion between elements.

Another object of this invention is to provide apparatus for effecting relative motion by means of structure which is capable of performing a large variety of functions.

These objects are accomplished in accordance with a preferred embodiment of the invention by apparatus that includes a guide surface and a thin, resiliently flexible elongated element superimposed on the guide surface. Longitudinally spaced portions of the element engage the guide surface and an intermediate portion of the element is elastically arched away from the guide surface in a lobe. The lobe is capable of progressing along the element by successively peeling portions of the element away from the guide surface at one end of the lobe while converging other portions of the element into engagement with the guide surface at the opposite end of the lobe. Thus, the lobe is displaced relative to the guide surface. As the lobe progresses past a portion of the element, that portion advances relative to the guide surface in the direction of movement of the lobe relative to the guide surface.

DESCRIPTION OF THE DRAWINGS Various preferred embodiments of the invention are illustrated in the accompanying drawings in which:

FIG. 1 is a schematic view of the guide means and the elongated element of the apparatus of this invention;

FIG. 2 is an enlarged schematic view of a portion of the guide means and element of FIG. 1;

FIG. 3 is a schematic view of a switch incorporating the apparatus of this invention;

FIG. 4 is a cross-sectional view of the switch along the line 4--4 in FIG. 3;

FIG. 5 is a cross-sectionalview, partially schematic, of a valve incorporating the apparatus of this invention;

FIG. 6 is a cross-sectional view of the valve along the line 6-6 in FIG. 5;

FIG. 7 is a top plan view of a non-uniform band in accordance with this invention;

FIG. 8 is a cross-sectional view of the band along the line 8-8 in FIG. 7;

FIG. 9 is a top plan view of another non-uniform band;

FIG. 10 is a cross-sectional view of the band along the line 10-10 in FIG. 9;

FIG. 1 l is a schematic view of a device incorporating the apparatus of this invention;

FIG. 12is a cross-sectional view of the device along the line l2--l2 in FIG. 11;

FIG. 13 is a side elevational view of a switch incorporating apparatus of this invention;

FIG. 14 is a cross-sectional view of the apparatus along the line l4-l4 in FIG. 13;

F IG. 15 is a cross-sectional view of the apparatus along the line l5-15 in FIG. 13;

FIG. 16 is a schematic view of a meter incorporating the apparatus of this invention; and

FIG. 17 is a cross-sectional view of the meter along the line 17-17 in FIG. 16.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, the apparatus of this preferred embodiment includes an elongated element in the form of a band 2 and a guide 4. The band is formed of a thin, resiliently flexible material and is superimposed on the surface 6 of the guide. The band illustrated in FIG. 1 is rectangular in cross section with a greater width than thickness. The band has a uniform thickness and width throughout its length. The surface 6 of the guide 4 is substantially cylindrical in this embodiment and has a width that is greater than the width of the band 2. One end of the band is secured to the guide 4 by a clamp 8 which prevents relative movement between the band 2 and the surface 6. The opposite end of the band is secured to the guide 4 by a clamp 10 after displacing the free end of the band toward theclamp 8 sufficiently to form a lobe l2.

The curvature of the surface 6 imposes bending moments on the band at the locations where the band engages the surface 6 at opposite ends of the lobe 12. These bending moments tend to shorten the length of the lobe and urge the portions of the band between the lobe and the clamps 8 and 10 against the surface 6. As shown in FIG. 1, the length L of the lobe 12 extends from the position on the band beyond which the band is supported solely by the surface 6. The band 2 should have sufficient resistance to plastic deformation to avoid becoming permanently set in the shape of the lobe 12. The band should also have sufficient stiffness to retain its cross-sectional shape and to support the bending moment, but it should not be so stiff that fracture or permanent set occurs at the lobe. It is also necessary for the band to be sufficiently resistant to longitudinal compression to avoid collapsing the lobe. The height H of the band lobe 12 is indicated in FIG. 1 as the distance between the surface 6 and the opposite face of the band 2. It is apparent from FIG. 1 that the length of band required to form the lobe 12 is greater than the length of the surface 6 between the opposite ends of the lobe.

Since the surface 6 of the guide has a uniform curvature between the clamps 8 and 10, the bending moments induced at the opposite ends of the lobe 12 remain constant regardless of the position of the lobe 12 along the surface 6. The lobe, therefore, is stable at any position along the surface 6 and is free to progress along the surface between the clamps 8 and 10.

The path of a point on the band as the lobe progresses relative to the band is shown schematically in FIG. 2. As the lobe l2 progresses from the position shown in full lines to the position shown in dotted lines in FIG. 2, a midpoint between the surfaces of the band 12, indicated at 14 follows the path indicated by the arrows in FIG. 2. As the front end of the lobe 12 passes over the point 14, the band is lifted from the surface 6 in a direction that is initially almost perpendicular to the surface 6. The band is progressively displaced away from the surface 6 until it approaches the apex of the lobe 12. It should be noted that the band portion that is momentarily at the apex of the lobe is moving in the opposite direction from the movement of the lobe. On the rear side of the lobe 12, the point 14 on the band progressively converges toward the surface 6 and after the rear end of the lobe has passed, the point 14 is positioned at the location indicated at 14 in FIG. 2. The height of the path h is equal to the height H in FIG. 1 less the thickness of the band 2. The distance cl is equal to the difference between the length L as measured along the surface 6 and the length of the band that forms the lobe 12 between the opposite ends of the lobe. If the lobe 12 were progressed backward from the position shown in dotted lines to the position shown in full lines in FIG. 2, each segment of the band would follow the path from the point 14' to the point 14, as shown in FIG. 2. Thus, the apparatus of this invention is capable of advancing the band longitudinally in either direction relative to the surface 6 a predetermined distance without sliding.

An electrical switch embodying the apparatus of this invention is illustrated in FIGS. 3 and 4. The mechanism includes a guide 16 having a surface 18 which is substantially cylindrical. A band 20 of rectangular cross section is secured at opposite ends to the guide 16 by clamps 22 and 24. The length of the band 20 between the clamps 22 and 24 is greater than the arcuate length of the surface 18 on which the band is supported, thereby causing the band to form a loop 26. A segment 28 is mounted for swinging movement on a shaft 30. The opposite ends of the shaft are journaled in suitable stationary bearings 32. The segment 28 has a contact surface 34 which is substantially cylindrical and concentric with the axis of rotation of the shaft 30. The axis of curvature of the cylindrical surface 18 of the guide 16 also coincides with the axis of rotation of the shaft 30. The surface 43 of the segment 28 bears against the surface of the band 20 at the apex of the lobe 26 and preferably the radial distance between the surface 34 and the surface 18 is less than the free height of the lobe 26, so that the frictional force between the surface of the band 26 and the surface 34 prevents slidmg.

When the segment 28 swings about the shaft 30, a longitudinal force is applied to the band 20 in the direction of movement of the surface 34. As shown in FIG. 2, this causes the lobe 26 to be displaced along the surface 18 in the opposite direction. A connecting rod 36 is attached to the segment 28 to impart swinging motion to the segment. Electrical contacts 38 and 40 are mounted in the surface of the guide 16. These contacts are preferably insulated from the guide 16 and from each other. The band 20 preferably provides a conductive path for electric current between the terminals 38 and 40.

In order to operate the switch of FIGS. 3 and 4, the rod 36 is displaced toward the left as viewed in FIG. 3 causing the segment 28 to swing clockwise about the shaft 30. This motion is transmitted to the lobe 26 causing the lobe to move toward the right. As the front end of the lobe 26 passes the terminal 40, the band is lifted away from the terminal, thereby breaking the electrical circuit with the terminal 40 while maintaining connection with the terminal 38. Subsequently, when the segment 28 swings in the opposite direction, the lobe is moved toward the left, as viewed in FIG. 3, thereby reestablishing contact with the terminal 40. Continued movement of the rod 36 toward the right disconnects the terminal 38 from the band 20 when the end of the lobe has moved past the terminal 38. Although only two terminals 38 and 40 are illustrated in FIG. 3, it is apparent that a series of terminals may be provided on the surface of the guide 16 for sequential circuit making and breaking by movement of the lobe 26 in response to rotation of the segment 28.

Another embodiment incorporating the apparatus of this invention is illustrated in FIGS. 5 and 6. In this embodiment, a valve body 44 has a chamber 46 in which opposed inner and outer walls 48 and 50 are cylindrical and have a common center of curvature. A thin, resiliently flexible band 52 is mounted in the chamber 46 by means of clamps 54 which are secured to the wall 50 of the body 44. The band 52 has a greater length than the length of the wall 50 between the clamps 54 and is arched in a lobe 56. The free height of the lobe 56 is substantially greater than the radial distance between the inner and outer walls 48 and 50, so that the lobe is partially compressed. The compression of the lobe increases the bending moments in the lobe.

The inner wall 48 has a pair of transverse grooves 58 which allow the lobe 56 to expand slightly upon moving into either of the grooves 58. The grooves serve as a detent for retaining the lope at a predetermined position along the wall 50. A fluid inlet port 60 and a fluid outlet port 62 are provided in the body 44 in communication with the chamber 46, as shown in FIG. 5. An O-ring seal 64 is mounted in a recess in the wall 50 around the opening of the port 62.

An actuator 66 for displacing the lobe 56 is mounted in a recess 68 in the chamber 46. The actuator includes a rectangular frame which supports cross bars 70 and 72 for swinging movement about a pivot shaft 74 that is mounted in bearings 76. A connecting rod 78 extends through the wall of the body 44 andis connected with the frame of the actuator 66. A suitable seal 80 is provided around the rod 78 to prevent leakage of fluid from the chamber 46.

In operating the valve of FIGS. 5 and 6, the lobe 56 is initially in the position shown in FIG. 5 with the apex of the lobe received in the left-hand groove 58. The band adjacent the left-hand end of the lobe 56 is spaced outwardly from the port 62, so that fluid is free to flow from the inlet 60 through the outlet 62. The cross bar 72 is in engagement with the surface of the band 52 adjacent the opposite end of the lobe 56. When the rod 78 is pushed upwardly, the crossbar 72 exerts a force on the band that is directed generally perpendicular to the wall 50 and preferably corresponds to the direction of initial movement of the band as illustrated in FIG. 2. This movement causes the lobe 56 to move toward the right as viewed in FIG. 5 after the detenting resistance of the groove 58 is overcome. Thelobe continues to move until the apex of the lobe is received in the righthand groove 58. When the lobe 56 is seated in the right-hand groove 58, as shown in dotted lines in FIG. 5, the band portion above the outlet port .62 is no longer a part of the lobe 56 and therefore is pressed tightly against the arcuate wall of the chamber 46, thereby sealing against the flow of liquid outwardly through the port 62. The fluid pressure in the chamber 46 is exerted against the exposed surface of the band 52 to urge the band into tightly sealing relation with the ring 64.

When the valve is to be opened again, the rod. 78 is displaced downwardly causing the opposite cross bar 70 to push against the band in a direction generally perpendicular to the wall 50, causing the lobe 56 to be displaced from the right-hand groove 58 to the left-hand groove 58, thereby again uncovering the port 62. This action is particularly advantageous in a fluid valve such as this where the fluid pressure differential on opposite sides of the band tends to hold the band tightly against the seal ring 64. Since the band is progressively peeled away from the wall 50, only a small force on the rod78 is necessary to overcome the hydrostatic forces acting on the band and to open the valve.

The various bands illustrated and described with respect to the embodiments of FIGS. 1 to 6 have a rectangular cross section of substantially greater width than thickness and the cross section of the band is uniform throughout the length of the band. Other shapes and types of bands that might be utilized in place of the band shown in FIGS. 1 to 6 are illustrated in FIGS. 7to l0.

In FIGS. 7 and 8, a band 82 having a rectangular cross section is illustrated. The width of the band, however, is not uniform throughout the length of the band. There are notches 84 and a slot 86 in the band which alter the characteristics of movement of the lobe formed by the band 82. The cross-sectional area of the band is reduced at the notches 84 and at the slot 86. The notches 84 extend over a short length of the band, while the slot 86 is relatively longer. When the notches 84 are positioned at the apex of the lobe, and the remainder of the band that forms the lobe has a uniform cross-sectional area, the bending moments in the lobe are balanced. However, when the band is displaced so that the notches 84 are between the apex and one end of the lobe, the notches 84 have much less resistance to bending than does the full width of the band in the lobe on the other side of the apex. This unbalance urges the lobe to move in a direction that would return the notches 84 to the apex of the lobe. Thus, the notches 84 cause the band to remain at a preselected position with respect to the guide surface. In the same way the slot 86 reduces the resistance to bending, but due to the length of the slot, the preferred position of the apex relative to the band extends the length of the slot 86.

In FIGS. 9 and 10, the lateral edges of the band 88 converge uniformly toward one end of the band, so that the cross-sectional area of the band changes uniformly with respect to its length. A lobe having a band of the shape shown in FIGS. 9 and 10, tends to move in the direction of smaller cross-sectional areas at the apex. Therefore, a greater external force is required for movement of the lobe in one direction than in the other.

Although each of the bands 82 and 88 have a uniform thickness, it is also possible to vary the thickness of the band in order to change the stiffness. The thickness of the band, however, has, a far greater effect on the change of stiffness than does the width of the band and therefore the preferred characteristics are more easily obtained by changing the width.

FIGS. 13 and 14 illustrate apparatus utilizing an elongated element 98 which has a substantially equal width and thickness, and is referred to as a wire. The wire 98 is secured in a guide shown schematically at 100. An actuator ,102 which has lateral flanges is supported for sliding movement by tracks 104 on the guide 100. The actuator and the guide have opposed arcuate grooves 106 and 108 formed therein. The wire 98, which is resiliently flexible, is arranged in a lobe l 10 and is secured at its opposite ends to the guide 100 by welding, or other suitable means. The grooves 106 and 108 prevent lateral displacement of the wire 98. Upon reciprocating movement of the actuator 102 along the tracks 104, a longitudinal force is transmitted by friction to the lobe 110 which causes the lobe to progress along the wire relative to the groove 108 in the direction opposite to the direction of movement of the actuator 102.

The guide surface that supports the elongated element may have a shape other than cylindrical. In FIG. 13, an electrical switch is illustrated schematically. The switch includes a guide 112 having a guide surface 114 that is substantially flat. A band 116 extends along the surface 114 and is secured to the guide 112 by clamps 118 and 120. The length of the band 116 between the clamps 118 and 120 is greater than the length of the surface 114, thereby causing the band to arch away from the surface 114 in a lobe 122. An actuator 124 is suspended over the surface 114 for swinging movement on a shaft 126. The actuator 124 has a surface 128 opposite the guide surface 114. The actuator surface 128 engages the apex of the lobe 122 and compresses the lobe between the surfaces 114 and 128. If the surface 128 were removed, the lobe 122 would extend approximately the entire length of the surface 114 between the clamps 118 and 120 and would have a height greater than the height of the lobe shown in FIG. 13. When the height of the lobe is reduced by compressing it, there is a corresponding reduction in the length of the lobe as the bending moments are increased at opposite ends of the lobe. It is this compressed condition that is illustrated in FIGS. 13 and 14.

The compressed lobe 122 is capable of progressing along the band 1 16 from the position shown in full lines in FIG. 13 to the position shown in dotted lines. This progression also displaces the lobe along the surface 114. The actuator 124 effects progression of the lobe by swinging about the shaft 126 from the position shown in full lines to the position shown in dotted lines in FIG. 13. Movement of the surface 128 toward the right, as viewed in FIG. 13, is transmitted to the band 116 at the apex of the lobe to cause the lobe to move toward the left. The extent or movement of the surface 126, however, causes the lobe to progress only a short distance along the band 116 toward the clamp 120. When the actuator is in the position shown in dotted lines in FIG. 13, the surface 128 is inclined relative to the surface 114. As a result, the bending moment at the righthand end of the lobe are greater than the bending moments at the left-hand end of the lobe and the lobe tends to progress toward the left.to the position shown in dotted lines in FIG. 13. In that position, the clamp 120 prevents further progression of the lobe and the lobe remains stationary until the actuator swings over to the position shown in full lines which causes the lobe to progress back to its original full line position.

Switch contacts 130 and 132 are mounted in the guide 112 and insulated from the guide. An insulated terminal 134 is also mounted in the guide 112 adjacent the clamp 120. As shown in FIG. 15, the band 116 has a conductive strip 136 on the surface of the band that engages the guide surface 114. The remainder of the band is preferably nonconductive.

The conductive strip includes a pair of lateral branches 138 and 140. These branches are spaced apart from each other lengthwise of the band a distance corresponding to the lengthwise displacement of the band as the lobe 122 passes from one end of the surface 114 to the other. This distance corresponds to the distance marked d in FIG. 2. The relative positions of the contacts 130 and 132 are shown schematically in FIG. 15.

- When the actuator 124 is displaced from the position shown in full lines in FIG. 13 to the position shown in dotted lines, the lobe 122 moves toward the left and as the lobe passes over the contacts 130, the branch 138 is lifted away from the contacts 130 and as the lobe approaches the position shown in dotted lines in FIG. 13, the branch 140 is displaced into alignment with the contacts 132 while the other branch 138 is displaced lengthwise from the contacts 130. As a result, a circuit is completed from the terminal 134 to the contacts 132 when the lobe is at the position shown in dotted lines in FIG. 13 and the terminals 130 are disconnected. When the lobe is at the position shown in full lines in FIG. 13, the contacts 130 are connected with the terminal 134 and the terminals 132 are disconnected.

Another embodiment of the invention is illustrated in FIGS. 16 to 18. In this embodiment, a meter movement is provided by a pair of opposed bands driven by a wheel. A housing indicated schematically at 142 has a pair of opposed arcuate surfaces 144 and 146. A thin, resiliently flexible band 148 is superimposed on the surface 144 and secured at its opposite ends by clamps 150. The band 148 is arched in a lobe 152 which projects toward the opposite surface 140. A second resiliently flexible band 154 is superimposed on the surface 146 and secured at its opposite ends by clamps 156. The band 154 is arched in a lobe 158 which projects toward the opposite surface 144. A wheel 160 is positioned between the lobes 152 and 158 and is journalled for rotation in bearings 162. The wheel 160 is connected with a rotary shaft 164 and the periphery of the wheel is in frictional engagement with both bands 244 and 250. The upper band 148 has a pair of arms 166 which are rigidly secured along the edge of the band in the lobe 152. An arcuate scale 168 is pivotally supported at each end on the ends of the arms 166. A pointer 170 is rigidly secured to the other band 154 along the edge and projects over the scale 168.

When the wheel 160 rotates in a clockwise direction, successive portions of the band 154 at the apex of the lobe 158 are displaced toward the left. This movement causes the pointer 170 to swing counterclockwise across the scale 168. At the same time, the wheel displaces successive portions of the band 148 at the apex of the lobe 152 toward the right, thereby swinging the arms 166 counterclockwise and displacing the scale 168 toward the right as viewed in FIG. 16. The relative motion between the pointer 170 and the scale 168 provides amplification of the rotation of the wheel 160.

The basic combination of the guide surface and an elongated element superimposed on the guide surface with a lobe that progresses relative to the element provides a large variety of actions which may be incorporated in motion transmitting apparatus or other apparatus. By varying the shape of the guide surface, or the stiffness of the element, a large variety of motions are possible. The apparatus of this invention is particularly suitable for devices in which the input energy is relatively small because these apparatus function with very little frictional resistance and for this reason the efficiency is relatively high. Also, the apparatus of this invention is capable of providing very large amplification or reduction of motion between the input and output.

An input motion can be applied to the lobe in various directions to cause movement of the lobe relative to the guide surface as desired. Also, the fact that a location on the element is displaced longitudinally a predetermined distance relative to the guide surface each time the lobe passes is useful for a variety of indexing functions.

While this invention has been illustrated and described by several preferred embodiments, it is recognized that variations and changes may be made therein, without departing from the invention as set forth in the claims.

WHAT IS CLAIMED IS:

1. Apparatus comprising means having a guide surface, an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe, said lobe having opposite ends adjacent said guide surface and an apex spaced from said guide surface and being between said opposite ends, and drive means for selectively progressing said lobe longitudinally of said element and thereby displacing said lobe along said guide surface without sliding of said element relative to said guide surface, said drive means being spaced from said apex and engaging said lobe adjacent at least one of said opposite ends, said drive means being operable to displace said one end selectively away from said guide surface.

2. The apparatus according to claim 1 wherein said elongated element is a band.

3. The apparatus according to claim 1 wherein said guide surface is concave.

4. Apparatus comprising:

means forming a guide surface;

a resiliently flexible element engaging said surface at a pair of locations spaced apart on said element and arching away from said surface in a lobe extending between said locations, said lobe having an apex spaced from said guide surface;

a drive member having a drive surface spaced from said guide surface and in opposed relation to said guide surface, said apex of .said lobe beingin engagement with said drive surface and said lobe being confined between said drive surface and guide surface; and

means for selectively moving one of said surfaces relative to the other of said surface longitudinally of said element, thereby flexing said element to progress said lobe along said surfaces with said element peeling away from said guide surface at one end of said lobe and converging onto said guide surface at the opposite end of said lobe.

5. The apparatus according to claim 4 wherein said guide surface is concave.

6. The apparatus according to claim 1 wherein said guide surface means has a port in said surface, said lobe being movable selectively tocover said portby saidelement and to uncover saidport.

7. Apparatus comprising:

means having a guidesurface;

an elongated element extending along saidguide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe;

means for flexing said element to progress said lobe along said element in one longitudinal direction while a point fixed on said element at the apex of said lobe moves relative to said lobe in a direction 5 opposite to said one direction; and

second means having a guide surface in opposed and spaced relation to said first-mentioned guide surface, said element engaging said second surface at the apex of said lobe.

8. The apparatus according to claim 7, wherein said element is a band.

9. The apparatus according to claim 7 wherein another point fixed on said element at one end of said lobe is displaced outwardly from said surface upon flexing said element to progress said lobe along said element in said one direction.

10. Apparatus comprising: means having a guide surface;

an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe; and

means for flexing said element to progress said lobe along said element in one longitudinal direction while a point fixed on said element at the apex of said lobe moves relative to said lobe in a direction opposite to said one direction and another point fixed on said element at one end of said lobe is displaced outwardly from said surface upon flexing said element to progress said lobe along said element in said one direction and a third point fixed on said element at the opposite end of said lobe is displaced toward said surface upon flexing said element to progress said lobe along said element in said one direction, said lobe defining an interior space between said element and said guide surface, said interior space being unobstructed to allow said lobe to progress along said guide surface, said flexing means being on the outside of said interior space.

11. The apparatus according to claim 10 wherein said elementhas a nonuniform stiffness along its length, whereby said element is biased toward a preferred position of said lobe relative to said surface.

12. Apparatus comprising means having a guide surface;

a resiliently flexible elongated element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe;

said lobe being capable of progressing along said element to displace said lobe along said surface, said lobe having an apex; and

means for engaging said element adjacent 'said apex, said engaging means being movable longitudinally of said element, whereby movement of said engaging means in one direction imparts motion to said lobe in the opposite direction.

13. The apparatus according to claim 12 including means for securing said elongated element to said surface at a pair of locations longitudinally spaced along said element at a greater distance than said spaced element portions, whereby said element is movable along said surface between said securing means.

14. The apparatus according to claim 12 wherein said lobe is movable between a first position and a second position relative to said guide surface, and output means on said guide surface positioned to be operative when said lobe is in said first position and inoperative when said lobe is in said second position.

15. The apparatus according to claim 13 wherein said guide surface is concave and said moving means has a convex surface in opposed relation with said guide surface.

16. Apparatus comprising:

means having a guide surface;

an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction andbeing resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe;

said lobe being capable of progressing along said element to displace said lobe along said guide surface between a first position and a second position;

means for displacing said lobe along said surface, said displacing means including an actuator mounted in said guide means, said actuator being in engagement with said elongated element at one end of said lobe in said first position and being inoperative for progressing said lobe when said lobe is in said second position, whereby said actuator lifts said element away from said surface at said one end of said lobe when said lobe is in said first 35 position and causes said lobe to progress from said first position to said second position.

17. The apparatus according to claim 16 including a second actuator spaced longitudinally of said surface from said first-mentioned actuator, said second actuator being in position for lifting said element away from said guide surface at the opposite end of said lobe when said lobe is in said second position, thereby displacing said lobe from said second position to' said first position.

18. Apparatus comprising:

means forming a pair of opposed guide surfaces;

a resiliently flexible elongated element having longitudinally spaced portions engaging one of said surfaces and an intermediate portion elastically arched away from said one surface in a lobe with the apex of the lobe engaging the other of said surfaces; said lobe being capable of progressing along said element to displace said lobe along said surfaces;

the spacing between said surfaces being greater at one position of said lobe than at another position of said lobe along said surfaces; said spacing biasing said lobe toward said position of greater spacing.

19. The apparatus according to claim 18 including means for changing the spacing along said surfaces, whereby the bias of said lobe is changed.

20. The apparatus according to claim 18 wherein said other surface has a depression therein at said first position, whereby said lobe apex seeks to align with said depression.

21. The apparatus according to claim 19 wherein said surfaces are movable relative to each other to change the spacing between said surfaces at one position relative to another position along said surfaces. 

1. Apparatus comprising means having a guide surface, an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe, said lobe having opposite ends adjacent said guide surface and an apex spaced from said guide surface and being between said opposite ends, and drive means for selectively progressing said lobe longitudinally of said element and thereby displacing said lobe along said guide surface without sliding of said element relative to said guide surface, said drive means being spaced from said apex and engaging said lobe adjacent at least one of said opposite ends, said drive means being operable to displace said one end selectively away from said guide surface.
 1. Apparatus comprising means having a guide surface, an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe, said lobe having opposite ends adjacent said guide surface and an apex spaced from said guide surface and being between said opposite ends, and drive means for selectively progressing said lobe longitudinally of said element and thereby displacing said lobe along said guide surface without sliding of said element relative to said guide surface, said drive means being spaced from said apex and engaging said lobe adjacent at least one of said opposite ends, said drive means being operable to displace said one end selectively away from said guide surface.
 2. The apparatus according to claim 1 wherein said elongated element is a band.
 3. The apparatus according to claim 1 wherein said guide surface is concave.
 4. Apparatus comprising: means forming a guide surface; a resiliently flexible element engaging said surface at a pair of locations spaced apart on said element and arching away from said surface in a lobe extending between said locations, said lobe having an apex spaced from said guide surface; a drive member having a drive surface spaced from said guide surface and in opposed relation to said guide surface, said apex of said lobe being in engagement with said drive surface and said lobe being confined between said drive surface and guide surface; and means for selectively moving one of said surfaces relative to the other of said surface longitudinally of said element, thereby flexing said element to progress said lobe along said surfaces with said element peeling away from said guide surface at one end of said lobe and converging onto said guide surface at the opposite end of said lobe.
 5. The apparatus according to claim 4 wherein said guide surface is concave.
 6. The apparatus according to claim 1 wherein said guide surface means has a port in said surface, said lobe being movable selectively to cover said port by said element and to uncover said port.
 7. Apparatus comprising: means having a guide surface; an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe; means for flexing said element to progress said lobe along said element in one longitudinal direction while a point fixed on said element at the apex of said lobe moves relative to said lobe in a direction opposite to said one direction; and second means having a guide surface in opposed and spaced relation to said first-mentioned guide surface, said element engaging said second surface at the apex of said lobe.
 8. The apparatus according to claim 7, wherein said element is a band.
 9. The apparatus according to claim 7 wherein another point fixed on said element at one end of said lobe is displaced outwardly from said surface upon flexing said element to progress said lobe along said element in said one direction.
 10. Apparatus comprising: means having a guide surface; an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in iTs transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe; and means for flexing said element to progress said lobe along said element in one longitudinal direction while a point fixed on said element at the apex of said lobe moves relative to said lobe in a direction opposite to said one direction and another point fixed on said element at one end of said lobe is displaced outwardly from said surface upon flexing said element to progress said lobe along said element in said one direction and a third point fixed on said element at the opposite end of said lobe is displaced toward said surface upon flexing said element to progress said lobe along said element in said one direction, said lobe defining an interior space between said element and said guide surface, said interior space being unobstructed to allow said lobe to progress along said guide surface, said flexing means being on the outside of said interior space.
 11. The apparatus according to claim 10 wherein said element has a nonuniform stiffness along its length, whereby said element is biased toward a preferred position of said lobe relative to said surface.
 12. Apparatus comprising means having a guide surface; a resiliently flexible elongated element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe; said lobe being capable of progressing along said element to displace said lobe along said surface, said lobe having an apex; and means for engaging said element adjacent said apex, said engaging means being movable longitudinally of said element, whereby movement of said engaging means in one direction imparts motion to said lobe in the opposite direction.
 13. The apparatus according to claim 12 including means for securing said elongated element to said surface at a pair of locations longitudinally spaced along said element at a greater distance than said spaced element portions, whereby said element is movable along said surface between said securing means.
 14. The apparatus according to claim 12 wherein said lobe is movable between a first position and a second position relative to said guide surface, and output means on said guide surface positioned to be operative when said lobe is in said first position and inoperative when said lobe is in said second position.
 15. The apparatus according to claim 13 wherein said guide surface is concave and said moving means has a convex surface in opposed relation with said guide surface.
 16. Apparatus comprising: means having a guide surface; an elongated element extending along said guide surface, said element being substantially inelastic in its longitudinal direction and being resiliently flexible in its transverse direction toward and away from said guide surface, said element having longitudinally spaced portions engaging said surface and an intermediate portion elastically arched away from said surface in a lobe; said lobe being capable of progressing along said element to displace said lobe along said guide surface between a first position and a second position; means for displacing said lobe along said surface, said displacing means including an actuator mounted in said guide means, said actuator being in engagement with said elongated element at one end of said lobe in said first position and being inoperative for progressing said lobe when said lobe is in said second position, whereby said actuator lifts said element away from said surface at said one end of said lobe when said lobe is in said first position and causes said lobe to progress from said first position to said second position.
 17. The apparatus according to claim 16 including a second actuator spaced longitudinally of said surface from said first-mentioned actuator, said second actuator being in position for lIfting said element away from said guide surface at the opposite end of said lobe when said lobe is in said second position, thereby displacing said lobe from said second position to said first position.
 18. Apparatus comprising: means forming a pair of opposed guide surfaces; a resiliently flexible elongated element having longitudinally spaced portions engaging one of said surfaces and an intermediate portion elastically arched away from said one surface in a lobe with the apex of the lobe engaging the other of said surfaces; said lobe being capable of progressing along said element to displace said lobe along said surfaces; the spacing between said surfaces being greater at one position of said lobe than at another position of said lobe along said surfaces; said spacing biasing said lobe toward said position of greater spacing.
 19. The apparatus according to claim 18 including means for changing the spacing along said surfaces, whereby the bias of said lobe is changed.
 20. The apparatus according to claim 18 wherein said other surface has a depression therein at said first position, whereby said lobe apex seeks to align with said depression. 